MEMS MICROPHONE PACKAGE AND PACKAGING METHOD
A MEMS microphone package having improved acoustic properties, and to a packaging method, which involve adding a vent path in the packaging process to improve equilibrium between internal and external air pressure. The MEMS microphone package includes a MEMS microphone chip, in which a back plate and a diaphragm structure are formed in a body by using MEMS process techniques; a substrate for mounting the MEMS microphone chip thereon; a vent path which is formed between the MEMS microphone chip and the substrate by applying an adhesive only to a portion of the substrate and adhering the MEMS microphone chip to the substrate; and a case which is adhered to the substrate and forms a space for accommodating the MEMS microphone chip, wherein acoustic properties of the MEMS microphone package are improved as air pressure inside the MEMS microphone chip and air pressure outside the MEMS microphone chip form air equilibrium via the vent path.
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The present invention relates to a micro electro machining system (MEMS) microphone package, and more particularly, to an MEMS microphone package of which acoustic properties are improved by improving air equilibrium between inner air pressure and outer air pressure by adding a vent path during a packaging process and a method of packaging the MEMS microphone package.
BACKGROUND ARTSince researches on micro electro machining system (MEMS) microphones have been first reported by R. Hijab, et al. in the 1980s, researches have been made on various structures of microphones using MEMS process techniques and techniques for manufacturing the same. An MEMS process is based on semiconductor process techniques. Through the MEMS process, a thin-film with stable and adjustable material properties may be fabricated, batch process may be possible, and a small, inexpensive, and highly efficient microphone chip may be embodied. Furthermore, compared to a conventional electret condenser microphone, an MEMS microphone may be assembled and operated at a relatively high temperature, and thus, an MEMS microphone package may be assembled by using existing surface mounting devices (SMD) and techniques.
Generally, as shown in
Referring to
When a MEMS microphone chip is fabricated, a plurality of vent holes are formed in a diaphragm to maintain air equilibrium between inner air pressure and outer air pressure. However, due to technical limits of manufacturing technologies, if an excessive number of vent holes are formed in a diaphragm or diameter of a vent hole is excessive, capacitances formed by surface areas of a back plate and a diaphragm decrease, and thus, sensitivity of the diaphragm is deteriorated. As a result, characteristics of low frequency domain are deteriorated. On the contrary, if an insufficient number of vent holes are formed in a diaphragm or diameter of a vent hole is insufficient, sensitivity of the diaphragm is improved, but air equilibrium is insufficient. Therefore, air resistance is formed in a back chamber, and thus, abnormalities occur in response speed and sensitivity of the diaphragm.
The present invention provides a micro electro machining system (MEMS) microphone package of which acoustic properties are improved by improving air equilibrium between inner air pressure and outer air pressure by adding a vent path during attachment of an MEMS microphone chip and a method of packaging the MEMS microphone package.
Technical SolutionAccording to an aspect of the present invention, there is provided a micro electro machining system (MEMS) microphone package including a MEMS microphone chip, in which a back plate and a diaphragm structure are formed in a body by using MEMS process techniques; a substrate for mounting the MEMS microphone chip thereon; a vent path which is formed between the MEMS microphone chip and the substrate by applying an adhesive only to a portion of the substrate and adhering the MEMS microphone chip to the substrate; and a case which is adhered to the substrate and forms a space for accommodating the MEMS microphone chip, wherein acoustic properties of the MEMS microphone package are improved as air pressure inside the MEMS microphone chip and air pressure outside the MEMS microphone chip form air equilibrium via the vent path.
According to another aspect of the present invention, there is provided a method of packaging a MEMS microphone, the method including preparing a substrate; calculating a thickness of an adhesive to be applied to the substrate; applying the adhesive to a portion of the substrate to the calculated thickness, such that the adhesive is not applied to a portion in which a vent path is to be formed; adhering an MEMS microphone chip to the adhesive; drying the adhesive; and adhering a case to the substrate.
The substrate is any of a printed circuit board (PCB), a ceramic substrate, and a metal substrate, and sound holes are formed in any one of the case and the substrate.
Advantageous EffectsAn MEMS microphone package according to an embodiment of the present invention may have improved acoustic properties by overcoming limits of manufacturing an MEMS microphone chip by adding a vent path when an MEMS microphone is attached to a substrate. In other words, an MEMS microphone package according to the an embodiment of the present invention may maintain air equilibrium between inner air pressure and outer air pressure stably regardless of vent holes of an MEMS microphone chip, and thus, abnormalities may be prevented without deteriorating the sensitivity of a diaphragm.
BEST MODE FOR CARRYING OUT THE INVENTIONThe present invention will now be described more fully with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. The invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete.
As shown in
Referring to
Furthermore, as shown in
Therefore, an MEMS microphone package according to the present embodiment may maintain air equilibrium between inner air pressure and outer air pressure stably regardless of vent holes of the MEMS microphone chip 10, and thus, abnormalities may be prevented without deteriorating the sensitivity of the diaphragm 14.
As shown in
Referring to
Therefore, in the MEMS microphone package according to the present embodiment, the diaphragm 14 oscillates when external sounds are input via the sound holes 40a formed in the case 40. Here, air inside the MEMS microphone chip 10 (air in the back chamber) and air outside the MEMS microphone chip 10 freely flow in and out not only via the vent holes 14a, but also via the vent path 24. Therefore, a change of sound pressures due to oscillation of the diaphragm 14 may be quickly settled to equilibrium, and thus, the sensitivity and acoustic properties of an MEMS microphone package may be improved.
Referring to
While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims.
BRIEF DESCRIPTION OF THE DRAWINGSClaims
1. A micro electro machining system (MEMS) microphone package comprising:
- a MEMS microphone chip, in which a back plate and a diaphragm structure are formed in a body by using MEMS process techniques;
- a substrate for mounting the MEMS microphone chip thereon;
- a vent path which is formed between the MEMS microphone chip and the substrate by applying an adhesive only to a portion of the substrate and adhering the MEMS microphone chip to the substrate; and
- a case which is adhered to the substrate and forms a space for accommodating the MEMS microphone chip,
- wherein acoustic properties of the MEMS microphone package are improved as air pressure inside the MEMS microphone chip and air pressure outside the MEMS microphone chip form air equilibrium via the vent path.
2. The MEMS microphone package of claim 2, wherein sound holes are formed in at least one of the case and the substrate.
3. The MEMS microphone package of claim 1, wherein the substrate is any of a printed circuit board (PCB), a ceramic substrate, and a metal substrate.
4. The MEMS microphone package of claim 1, wherein at least one vent path is formed.
5. A method of packaging a MEMS microphone, the method comprising:
- preparing a substrate;
- calculating a thickness of an adhesive to be applied to the substrate;
- applying the adhesive to a portion of the substrate to the calculated thickness, such that the adhesive is not applied to a portion in which a vent path is to be formed;
- adhering an MEMS microphone chip to the adhesive;
- drying the adhesive; and
- adhering a case to the substrate.
6. The method of claim 5, wherein the substrate is any of a printed circuit board (PCB), a ceramic substrate, and a metal substrate, and
- sound holes are formed in at least one of the case and the substrate.
Type: Application
Filed: Feb 11, 2010
Publication Date: Nov 10, 2011
Applicant: BSE CO., LTD. (Incheon)
Inventors: Chung-Dam Song (Seoul), Chang-Won Kim (Incheon), Jung-Min Kim (Incheon), Won-Taek Lee (Incheon), Sung-Ho Park (Incheon)
Application Number: 13/144,587
International Classification: H01L 29/84 (20060101); H01L 21/58 (20060101);